Text books - Feynman's 'Lectures' Vol. III chapter 5
Originally posted by RedX
Well I'm self-studying quantum mechanics with The Feynman Lectures in Physics, volume III. I think it's a good book, but it might be too easy for you if you're a physics student . . .
If you want an eye opener in quantum physics read chaspter 5, pages 5-9 to 5-10 (or read the whole chapter and see where RF makes a conscious effort to bamboozle the reader). Feynman makes the most atrocious error in equating the experimental results of experiment 5:15 with 5:17. In 5:15 there is a Stern-Gerlach trnasition where the upper and the lower channels are blocked, thereby allowing only a fraction of the particles through the middle channel as 0S particles - he is anticipating the 0S particles to enter the S segment following the T segment. In 5:17 he states that there is a real, positive amplitude for a similar finding where the unblocked T segment also allows a positive amplitude for 0S particles - yes, they all sum to zero!. If this is true, and it isn't, then RF is saying that the 0S channel always allows positive amplitudes where the remaining channels must add amplitudes of the other two channels to the negative of the 0S amplitude. Rubbish.
Blocked configurations can not un der any circumstances be equated with unblocked arrangements, it just isn't within the limits of allowed scientific integrity to do so as RF baltantly did.
RF earlier in the chapter makes it abundantly clear that a wide open T segment is the same as no segment at all, thereby saying the input state is identical to the output state. As the input state to the unblocked segment was a base state +S particle, this is also the exit state and this state always will take the upper, +S channel when transitioning through an S segment, whether it is blocked or not.
He cons you with his "here's that old interference amplitude" again.One doesn't need interfernece amplitude to analyze these experiments.
A proper analysis of this chapter cuts the supporting rope to the guillotine blade now racing to nape of the neck of quantum theory - clean, quick and a tad bloody, but effective..
He makes it a "gee golly", when he states that opening more channels in the wide open mode allows "fewer particles through". Not until a few paragraphs later does he slide the fact in that only for rhe 0S and -S channelc in the final S segment is this statement true - no particles get through these channels. However, many more particles are allowed through than is the case of the blocked arrangement. In fact all the particles entering the wide open T segment make it through the S segment when the +S channel is open. Remember, the open T segment does not change the state of the particle, ergo, it is to be expected that all particles will transit through the +S channel. Earlier in the chapter he makes it clear that this is what is occurring.
There is somthing pathological about quantum theory. Anyone taking QT at face value will ultimately need some serious deprogramming in order to regain mental stability. But, hey, all PhD candidates have graduate advisors to talk matters over with.